SmogRank / South Korea / North Chungcheong / Okcheon
Okcheon, month by month
Okcheon has a measured daily mean on 882 days since 24 March 2024. Its worst month was March 2026, at 86 US AQI (28.0 µg/m³), 334th of 2,971 cities on that month's world ranking. Its cleanest was September 2025, at 33 US AQI (5.9 µg/m³). 2025 averaged 66 US AQI (16.9 µg/m³), against 58 US AQI (12.9 µg/m³) in 2024.
Every month since 2024
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
2 months
| Month | Why |
|---|---|
| Aug 2026 | 21 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 3 of 31 days measured; a month needs 22. The others: 5 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Okcheon's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| March 2026 | 8628.0 µg/m³ | 334thof 2,971 | Japan and South Korea, March 2026 South Korea, 9 to 12 March 2026 |
| February 2026 | 8627.9 µg/m³ | 288thof 2,866 | South Korea and Japan, 10 to 15 February 2026 South Korea, February 2026 |
| January 2025 | 8527.3 µg/m³ | 127thof 2,474 | Japan and South Korea, 17 to 24 January 2025 |
| December 2025 | 8426.9 µg/m³ | 342ndof 3,006 | South Korea, 29 to 30 December 2025 South Korea, 16 to 20 December 2025and 2 more |
| November 2025 | 8225.5 µg/m³ | 288thof 2,715 | South Korea, 13 to 14 November 2025 South Korea, 5 to 7 November 2025 |
| January 2026 | 8024.5 µg/m³ | 261stof 2,617 | South Korea and Japan, January 2026 |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Okcheon's worst days
| Day | US AQI | Episode |
|---|---|---|
| 21 Jan 2025 | 16677.0 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 22 Jan 2025 | 16676.7 µg/m³ | Japan and South Korea, 17 to 24 January 2025 |
| 16 Jan 2026 | 16372.2 µg/m³ | South Korea and Japan, January 2026 |
| 14 Feb 2026 | 16170.3 µg/m³ | South Korea and Japan, 10 to 15 February 2026 |
| 15 Jan 2026 | 15967.4 µg/m³ | South Korea and Japan, January 2026 |
| 13 Feb 2026 | 15763.8 µg/m³ | South Korea and Japan, 10 to 15 February 2026 |
| 29 Dec 2025 | 15561.0 µg/m³ | South Korea, 29 to 30 December 2025 |
| 7 Dec 2025 | 15459.4 µg/m³ | South Korea, 7 December 2025 |
| 5 Feb 2026 | 15459.2 µg/m³ | South Korea, February 2026 |
| 25 Mar 2025 | 14954.8 µg/m³ | Japan and South Korea, March 2025 |
Daily means, the highest since 24 Mar 2024; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Okcheon, South Korea, 24 Mar 2024 – 12 Oct 2026. Monitor data from Korea Air Ministry of Environment via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/kr/okcheon/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Okcheon now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 18:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).